It shows the polyphenol concentration of the cast out wort in mg/l (top row) as a function of the way the malt was crushed. The top header is: mash filter (pulverized grist), lautertun crushed dry, lautertun crushed conditioned and wet crushed. As you can see, in this case conditioned malt left 13% less polyhenols in the cast out wort.

While there seems to be a difference in the wort analytics this does not show if there will be a difference in taste. polyphenols are not necessarily and in some other section they of this book they are also considered as contributors to the body of the beer.

I hope I didn’t scare anyone into conditioning their malt now. I just thought that this was an interesting data point which I haven’t seen before.

Over the last week I've been reading practically every book and magazine I have so I can't remember which one or where I read it but it went into some depth about pH creeping up in the mash and how malt conditioning effected it. I do remember it saying that 2% moisture (misting) added to the grains about 15 to 20 minutes before crushing lessened the release of polyphenols. It also noted that polyphenols create some astringency. It also stated that the longer the mash water is allowed to stay in contact with the grain husks more polyphenols are created or released.

I don't know, I'm not a scientist but it makes sense to me and I believe it, especially after doing a couple of overnight mashes and having one which should have been right for my water come out fairly decent except for a finishing astringency. It tastes good while consuming it, has good mouthfeel going down but it dries my mouth afterward. Its almost like a bitter but its not really bitter. Its hard for me to describe it I guess. Anyway I'm dumping it because I can't bring myself to drink it anymore as I find myself anticipating the astringency everytime I do and I wouldn't give it to anybody either now.

… especially after doing a couple of overnight mashes and having one which should have been right for my water come out fairly decent except for a finishing astringency

It is a well known fact that longer mashes release more polyphenols and that the move to shorter mashing by German brewers has resulted in softer beers. The extreme of this thinking is endosperm mashing or Schrotmaischen, where you only mash the flour and grits first and return the husk fraction late in the mash before it is needed for lautering.

… especially after doing a couple of overnight mashes and having one which should have been right for my water come out fairly decent except for a finishing astringency

It is a well known fact that longer mashes release more polyphenols and that the move to shorter mashing by German brewers has resulted in softer beers. The extreme of this thinking is endosperm mashing or Schrotmaischen, where you only mash the flour and grits first and return the husk fraction late in the mash before it is needed for lautering.

Most large scale mills already have sieves that separate the husks from the grits before the grist are milled further. It just becomes a matter of diverting the husks into a separate grist case for later addition to the mash. It might be more complicated than that since you are very interested in minimizing the amount of endosperm that stays with the husks. I know of only two breweries that do that: Brauhaus Riegle and Trumer, and I never had any of these beers. It’s just not a commonly used practice.

At some point I want to give it a try. About 50% of the husks will be added back to the mash 10-15 min before lautering. They’ll need some time to convert the few endosperm pieces that are still sticking to the husks. If you are not going to be a purist you could also use rice hulls which would not add any additional starch to the mash.